Effects of osteoarthritis on radiographic measures of laxity and congruence in hip joints of Labrador Retrievers

Objective—To determine effects of hip joint osteoarthritis on radiographic measures of hip joint laxity and congruence. Design—Longitudinal study. Animals—40 Labrador Retrievers. Procedures—Dogs were assigned to 2 groups based on radiographic evidence of osteoarthritis. Dogs in the osteoarthritis group were free of osteoarthritis at initial radiographic evaluation (t1) and developed osteoarthritis by a subsequent radiographic evaluation (t2). Dogs in the nonosteoarthritis group had no radiographic osteoarthritis at either evaluation. Hip joint laxity was quantified by use of the distraction index (DI) from a distraction radiographic view and use of the Norberg angle (NA) from a ventrodorsal hip-extended radiographic view. The compression index (CI) from a compression radiographic view was used as a measure of joint congruence (concentricity). Results—Hip joint laxity (NA or DI) did not change over time in the nonosteoarthritis group. Mean hip joint laxity (NA and DI) for the osteoarthritis group was great...